digital terrain model software free download

So each map comes with it's own scale, evenly dividing the 256 grey values between the min and max Z as present in that one map. As a result most maps would only contain very dark grey, and almost no information. In order to use the same scale for all maps these 256 Z-levels would need to be used for the complete Z-range that can be found in the USA. A bitmap file can contain 256 grey values, so 256 Z-levels. This sounds rather awkward (in fact it is.) still it does make sense. You cannot just stitch two BMP files with elevation data, as in each BMP file the height information will be on a different scale !! The second issue is important when you need to combine two or more different maps in order to cover the area that you want to machine. Tiled view of the Bay area, and the two tiles used for this relief. Most important is the large TIFF file for each of the maps, containing the actual elevation data. In this ZIP file you will find four files for each of the maps, and some extra files with meta-data.

You will then receive an email with a link to the ZIP file to be downloaded. Select County (for this project San Francisco)Ĭheck 'National Elevation Dataset 10 Meter' (for our county 7 maps, 20.869 MB) and press ContinueĪs delivery method select FTP and press Continueįill in your name and address data and press Continue Select State (for this project California) Press that button and continue as follows: On this website you will see a large button GET DATA (see the picture above). The elevation data that you need is provided by the United States Department of Agriculture, and is called the Geospatial Data Gateway. These maps are ready for download in various formats, to facilitate your modeling.Left the NRCS geospatial data gateway, right the ZIP with elevation data files. presently contains extensive map coverage for technical applications including Air Dispersion Modeling, Human Health & Ecological Risk Assessment and Terrain Processing. WebGIS - Geographic Information Systems Resource - GIS

Digital terrain model software free download